Encapsulation of cement particles for self-healing mortars

Abstract

Cracks in cement-based materials are inevitable and compromise the durability of structures. Although unhydrated cement clinkers possess good self-healing capability, its service life is often unsatisfactory. In this study, cement powder was fabricated into dense cement particles using a wet granulation method, followed by encapsulation through the melt dispersion condensation method. The resulting capsules had cement particles as the core and glycerol tristearate-polyurea composites as the shell material. Final capsules exhibited good dispersibility and a clear core-shell structure. The average particle size was 900.5 ± 83.1 μm, with a core content of 56.6 wt%, and the compressive strength was approximately 7.6 MPa. The addition of capsules will affect the performance of the matrix. In self-healing mortars, about 80 % of the capsules broke within the cracks. Most importantly, the self-healing mortar after hydration for 28 days was able to completely heal cracks with widths below 100.0 μm, along with fully restoring its impermeability.